If you leave AT&T alone and don't change anything they seem to do OK with doing just what they were doing before. If you use the C - word (change) all bets are off. I still have nightmares of opening my cell phone bill and it was HOW MUCH???
It took me over a year and a analog letter to the AT&T headquarters to get the morons to understand how they were screwing up. Not one of the people on the phone support line could figure it out.